# Fundamentals of Graphing – Interactive tutorial

Should these data be plotted on a graph? Yes. You have multiple values for the independent variable (time), and the dependent variable clearly changes with respect to the independent variable.

Which variable will you plot on the y (vertical) axis? Height. By convention, we use the y axis for the dependent variable and the x axis for the independent variable. We refer to plotting the dependent variable versus the independent variable. Exceptions to this convention are rare.

## Decide on a plot type

In Microsoft Excel, if you select Insert/Chart... from the top menu or click on the "Chart Wizard" icon, a "Chart Wizard" window pops up. The Standard Types include a choice of conventional plot types and a few unconventional types as well. Some of the choices are illustrated below.

 column bar line pie XY (scattter) area doughnut other?

The choices "radar," "surface," "bubble," "stock," "cylinder," "cone," and "pyramid" are not included, for what is hoped are obvious reasons. Custom types are also excluded. Now from this "short list" select a plot type or types that would be most appropriate for these data, considering the nature of the data and the intentions of the investigator.

column
bar
line
pie
XY (scatter)
area
doughnut
other

## Previous conclusions

The times to take samples were determined by the investigator. Time is the independent variable.
The height of a seedling depended on the time it was sampled. Height is the measured quantity, making it the dependent variable

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Weekly height measurements for seedlings of Acer palmatum:

 week 0 2 4 6 8 10 12 measured 1.2 1.4 1.4 1.9 5.8 5.7 5.3 heights 0.3 0.5 2.0 3.0 2.9 4.8 5.1 in inches 1.1 1.0 2.3 3.8 4.9 4.8 8.5 1.1 1.7 2.2 2.6 3.7 8.2 8.2 1.0 1.8 2.4 3.5 5.6 6.1 7.0 1.5 2.2 2.0 2.3 4.8 4.8 5.5 1.3 1.5 2.0 3.1 1.1 8.3 5.6 0.8 1.5 2.1 3.1 4.6 6.1 2.2 1.7 1.7 2.5 4.3 4.2 7.4 4.8 1.5 1.6 1.6 5.0 5.1 3.7 8.4 1.6 1.2 2.7 1.8 3.8 4.3 4.3 1.1 1.2 1.5 2.8 7.4 4.3 5.9